1. Field of the Invention
The present invention relates generally to cardiac assist systems, and more particularly, relates to monitoring of cardiac assist systems which are powered by skeletal muscle.
2. Description of the Prior Art
Cardiac assist systems do not replace the human heart, but merely supplement it. Many techniques have been proposed using a variety of mechanical power sources. Typically these require some form of percutaneous energy transfer because of the difficulty in storing sufficient energy subcutaneously. Such systems are cumbersome and inconvenient for the patient, and are prone to infection along the percutaneous energy transfer path.
A technique holding a great deal of promise is to power the cardiac assist system from a surgically modified skeletal muscle. The cardiac assist system is thus powered by normal biochemical processes. U.S. Pat. No. 4,813,952 issued to Khalafalla teaches a number of configurations of a skeletal muscle powered cardiac assist system.
One problem peculiar to a skeletal muscle powered cardiac assist system is that the skeletal muscle must be conditioned to the constant load of continuous contraction/relaxation demanded of the myocardium U.S. Pat. No 4,411,268 issued to Cox teaches a technique for conditioning the skeletal muscle. Whereas the apparatus of Cox is effective to accomplish this conditioning, his system has no provisions for chronically monitoring the stability of the skeletal muscle following the conditioning process In practice this necessitates the attention of highly skilled medical personnel to monitor the operation of the skeletal muscle with sophisticated instrumentation, and to exercise manual control of the stimulation regimen with pulse generator programming equipment. Furthermore, neither Cox nor Khalafalla teach a real time monitoring mechanism, whereby the timing of the conditioning, maintenance, and stimulation pulses may be automatically adjusted to optimize efficiency of skeletal muscle contractions.